This invention relates to a method and apparatus for forming unique cigarette filters and combining the filters with a tobacco rod to form filter cigarettes.
Most of the presently known cigarette filters are generally formed from a continuous tow of cellulose acetate fibers into a long continuous rod. The continuous rod is then cut into appropriate lengths for processing which are called 4-ups and 6-ups in the industry. A 4-up is four single filters or two dual (2-up) filters while a 6-up is six single filters or three dual filters in length. The 4-up and 6-up filters are transported from the filter-making machine either manually or by an automatic conveying system to the hopper or a cigarette assembler machine.
The cigarette assembler takes the 4-up or 6-up filters and slits them into dual filter (2-up) lengths and attaches them to a tobacco rod being supplied to the assembler by a cigarette maker. A tobacco rod is attached to each end of the dual filter in the cigarette assembler to form a double cigarette unit. The double cigarette is then separated into two single cigarette units by slitting it at the center of the dual filter. The cigarettes are passed through various inspection systems before being transported either manually or automatically to a packer unit.
There are various types of filter configurations and materials used in the manufacture of filter cigarettes; however, in all instances, the filter is made on one machine in a continuous rod and then slit into 4-ups or 6-ups for use in a cigarette assembler which joins the filter to the tobacco rod.
In recent years, there have been many attempts to produce cigarette filters with better filtering efficiency and this filter research has produced many filters of varying configurations. Some are made completely of cellulose acetate while others are made of a combination of materials such as extruded plastics cores, activated charcoals, a combination of plastic tubes and cellulose acetate, etc. Generally the cellulose acetate filters are made into a continuous rod or tube and various operations are performed on the external surface of the rods to produce filters of different configurations. Some examples of such filters are disclosed in the following U.S. Pat. Nos. 3,752,166; 3,599,646; 3,690,326 and 3,648,711.
Most of these types of filters disclosed in the patents mentioned above utilize a high-surface area/high density theory of filtration as well as a cross fiber method of filtration. In other words, the smoke is exposed to a large surface area so the smoke velocity will be decreased, then the smoke is drawn through a denser filter medium than is used in a standard filter in a direction which is cross-wise to the direction fibers in the filter plug. Due to the more dense filter medium and the cross fiber path the smoke follows, there is more likelihood that the particulate matter entrained in the slowly traveling smoke will come in contact with a fiber and be removed from the smoke being inhaled.
Some examples of the extruded plastic filters are shown in the following U.S. Pat. Nos. 3,577,995; 3,577,996; 3,612,064 and 3,628,540. The filters disclosed in the above-mentioned patents are generally made of an extruded plastic body having a series of restrictive passages through which the smoke is directed. These restrictive passages cause an increase in the smoke velocity when the cigarette is inhaled. Baffles are located within the passages so that the smoke will impinge against them as it is drawn through the filter. This type of filter uses the impingement principle to produce a high efficiency filtration. The impingement technique results from the impaction of smoke on the baffles which causes particulate matter in the smoke to adhere to the baffles. As a residue builds up on the baffles, particulate matter entrained in the subsequently inhaled smoke impinges upon the baffle containing the residue and adheres more easily to this residued particulate matter, thereby being removed from the smoke.
Each of the above-mentioned filter configurations produces problems in the various manufacture operations to form the cigarette as well as increasing the cost of production. The cost of forming the high density cellulose acetate fibers is extremely high because the filter requires much more cellulose acetate material to produce the high efficiency filtration results. With cost of the filter unit itself being extremely high, this also will raise the cost of producing a filter cigarette unit. Furthermore, many of the configurations of filters formed with cellulose acetate have irregular peripheral surfaces, these irregular surfaces cause problems when trying to attach the tobacco rod to the filter which detracts from the quality of the cigarette as can be understood. This increases the cost of a cigarette unit because the quality control equipment has to be increased. Filters made from extruded plastic bodies produce many of the same difficulties as mentioned above. Especially, in the area of joining the filter to the tobacco rod.
A filter which will overcome the above-mentioned problems has been developed and an application has been filed on this unique filter. This related application is assigned to the assignee of this application and is entitled, "Filter Element for Cigarettes" which was filed on July 9, 1973, and assigned U.S. Ser. No. 377,858. This new and improved filter uses both the impingement and cross-fiber filtration principle for high efficiency filtration and is made solely of cellulose acetate.
The above-identified new filter reduces the density required by the high surface/high density filter while retaining the same efficiency. It also has a cylindrical body with a uniform peripheral surface which lends itself to better handling and joining with a tobacco rod. This filter configuration generally includes at least one bore extending through each end of the standard cellulose acetate filter plug, each bore terminating prior to the end of the plug. Generally the bores are parallel to the axis of the plug but are not aligned. The smoke is drawn into the bore and its velocity is increased because of the restrictive sizes of the bores. The smoke velocity being increased will produce an impinging effect when the smoke strikes the bottom of the bore, causing particulate matter to concentrate at the bottom of the bore. The particulate matter in subsequent inhalations of smoke will travel through the concentrated area and is more likely to contact and coheless with other particulate matter already deposited on the fibers and be removed from the smoke. The smoke passing through the concentrated particulate matter also passes from one bore to the other in a crosswise manner to produce a cross-fiber filtration. It can be seen that both impingement principle as well as a cross-fiber filtration principle are utilized in this new improved filter.
One of the main problems with developing such a filter, however, is to produce a method and apparatus to manufacture such a filter economically. It is believed that such a method and apparatus has been developed and set forth herein.